JPS604019A - Preparation of container with flange part - Google Patents

Abstract

PURPOSE:To perform uniform heat-sealing between the entire surface of a flange part and a cover part by forcing the part inside of the caved-in part of a blank into the cavity of a die. CONSTITUTION:The upper plunger 1 is lowered while the inner part of the lower cavity 3b is lowered by the upper plunger 1 and the lower plunger 2 pushing the inside central part 10a by the caved-in part 10d of the plastic blank 10. During the initial period of lowering, space and material are accumulated. When extrusion force is reduced to continue to lower the plungers, the quantity of material extending from the space between these plungers reduces, accordingly tension is applied to the material accumulated at the shell wall part 5'b' thereby said part continues to extend. At the completion of lowering, a space 12 is formed between the shell wall part 5'b and the inside 3b1 of the lower cavity. The shell wall part 5'b of substantially uniform wall thickness can be obtained by the control of extrusion force and lowering speed.

Description

DETAILED DESCRIPTION OF THE INVENTION More specifically, the present invention relates to a method for manufacturing a cassock-like container with an outer flange (herein simply referred to as flange) from a thermoplastic blank.

Traditionally, manufacturing of cup-shaped plastic containers with flanges is as follows:
Place the peripheral edge of the blank that corresponds to the flange on the stepped part of the die, and while holding it down with a presser with a flat bottom surface, insert the inner part of the peripheral edge into the cavity of the die using a plunger or air pressure. This was done by press-fitting to form the trunk wall and bottom. In this case, the upper surface of the flange part is slightly tilted inwards and downwards (hereinafter this phenomenon is referred to as "sagging"), or a slight bulge is formed on this upper surface (hereinafter this phenomenon is referred to as "waviness"). )easy.

Therefore, when heat-sealing the lid to the flange after filling the container with contents, the heat-sealing is not done evenly between the entire surface of the flange and the lid, and sufficient heat-sealing strength cannot be obtained. When the content is a positive internal pressure liquid such as beer, local peeling occurs in the heat-sealed portion, resulting in a problem that the sealing performance is likely to be impaired. 1 It is an object of the present invention to solve the problems of the prior art described above.

To achieve the above object, the present invention provides a method for manufacturing a cup-shaped container with a flange from a blank made of thermoplastic glass, in which a portion of the blank corresponding to the flange is connected to a shoulder of a die. , the annular small protrusion having an outer surface extending inwardly and upwardly in the axial direction is pressed by a presser formed on the inner end of the bottom surface, and the small protrusion is injected into the blank to form the injection part. The present invention provides a method for manufacturing a cup-shaped container with a flange portion, characterized in that a portion of the blank inside the injection portion is press-fitted into a cavity of the die in a state in which the blank is formed.

The present invention will be described below with reference to the drawings.

1 to 7, 1 is an upper flank 4, 2 is a lower plunger, 3 is a die, and 4 is a presser. The die 3 is fixed to a holding member (not shown), and is attached to a first
As shown in the figure, an upper cavity 3a and a lower cavity 3b are formed. The upper cavity 3a has a short cylindrical shape, and its inner diameter is set approximately equal to the outer diameter of the flank portion 5a of the plastic container 5 (FIG. 7) to be formed, while the lower cavity 3b has a cylindrical shape. The inner diameter is set equal to the outer diameter of the body wall portion 5b of the plastic container 5 to be formed. The inner surface 3al of the upper cavity 3a has a horizontal stepped portion 3C,
It is connected to the inner surface 3b□ of the lower cavity 3b.

The outer diameter of the upper plunger 1 is equal to the inner surface 3b of the lower capity.
, the clearance X (see FIG. 5) is determined to be larger than the wall thickness y of the body wall portion 5'b of the hollow molded body 5' to be press-stretched, for example, X - y. = 0.2~
It is set at around 0.8 key.

A guide hole 7 is formed in the axial direction in the upper plant holder l, and the lower end opening of the guide hole 7 is formed into a truncated cone-shaped plate ""i, xy-' c.
The conduit 7 to the is located below the level of the step portion 3C of the die 3, the electromagnetic valve is opened and pressurized air is supplied to the guide hole 7.

The upper plunger 1 is made of metal (such as tool steel),
A heater (not shown) is built in, and the bottom surface 1a and the side surface of the portion having a height approximately equal to at least the height of the body wall portion 5b of the plastic container to be formed]
, b (FIG. 5) are preferably maintained at a temperature that allows molecular orientation of the plastic. Further, the lower plunger 2 is configured to be slidable within the lower cavity 3b.

The presser 4 has a hollow portion 4a, and the upper plunger 1 is configured to be slidable along the inner surface of the hollow portion 4a. The bottom surface 4b of the presser 4 includes a flat portion 4b forming the majority of the bottom surface 4b, and a small annular protrusion 4b2 formed at the inner end of the bottom surface 4b. The flat part 4b+ is disposed to face the step part 3C, and the lower part 4C of the presser 4 is movable up and down within the upper cavity 3a, and its outer diameter is approximately equal to the inner diameter of the upper cavity 3a. , is set slightly smaller than that. The presser 4 is moved up and down via a rod 11 by a drive mechanism (for example, a hydraulic system), not shown.゛The upper plunger l and the lower syringer 2 are also moved up and down by a drive mechanism (for example, a hydraulic device) not shown, and the central part 10a of the plastic blank 10 is pressed between the bottom surface 1a of the upper syringe l and the upper surface 2a of the lower syringe 2. In order to be able to apply a controlled compressive force to the central portion 10a when the cylinder is introduced into the lower cavity 3b, a control mechanism (not shown) controls the difference in descending speed between the upper syringer 1 and the lower plunger 2. It is now possible to do so.

The plastic blank 10 is made of thermoplastic,
Preferably, the main material is a thermoplastic glass having molecular orientation. Examples of this type of plastic include crystalline polyolefin resins such as isotactic polyglohylene, high-density polyethylene, medium-density polyethylene, and low-density polyethylene, linear polyester resins such as polyethylene terephthalate, polycarbonate resin, and polyvinyl chloride resin. , nitrile resins, or copolymers or blends thereof. If the plastic container product is not particularly required to be transparent, it may be mixed with a filler such as talc, calcium carbonate, or mica flakes.

The plastic blank 10 is made of these molecularly oriented thermoplastics (7-1), or is composed mainly of these molecularly oriented thermoplastics and is coated with an oxygen gas barrier resin such as ethylene-vinyl alcohol. It is formed by cutting a sheet of a laminate or blend of a polymer, polyamide, cellulose resin, I-reacrylonitrile, polyvinylidene chloride, polyvinyl alcohol, etc. into a predetermined size. The thickness of the plastic blank 10 is substantially uniform and ranges from about 0.5 to 611111
1, more preferably approximately 2 to 4 tones. If it is thinner than about 0.5 mm, the plastic container 5
This is because during molding, breakage is likely to occur particularly at the bottom, and on the other hand, if it is thicker than about 6 mm, breakage is likely to occur near the flange.

The diameter of the plastic blank 1o is determined so that the plastic blank 10 can be placed on the stepped portion 3c and pressed by the presser pad 4, and so that a predetermined width of the flange portion 5a can be obtained. That is, the above diameter is approximately equal to the inner diameter of the inner surface 3a1 of the upper cavity 3a, or the inner diameter is equal to the inner diameter of the inner surface 3 of the lower cavity 3b.
It is set to the middle dimension of the inner diameter of b1.

The plastic container 5 using the above-mentioned molding apparatus is manufactured, for example, as follows.

First, as shown in FIG. 1, in a state 1 in which the upper roller 1 and the presser 4 are raised above the die 3,
Preferably, the peripheral edge 10b (the plastic container 5 to be formed (corresponding to the flange portion 5a) of the die 3 at the stepped portion 3 of the die 3.
Place it on C. At this time, preferably, the upper surface 2a of the lower silane gloss 2 is raised in advance to the same level as the stepped portion 3C.

Next, as shown in FIG. 2, the presser 4 is lowered and the peripheral edge 10b of the plastic blank 10 is moved to the stepped portion 3C.
Press down with a predetermined pressing force using the bottom surface 4b of the presser 4. The small protrusion 4b2 is made of plastic blank lO.
A recessed portion 10d is formed by recessing into the upper surface 10e.

After that, the upper plunger 1 is lowered, and the upper plunger 1 is lowered.
and lower syringe 2, plastic blank 1
A central portion 10a which is a portion inside the biting portion 10d of 0
While pressing , as shown in FIG.
descend inside. Early stages of descent (usually about 2
0 to 40) by increasing the compression amount of the central portion 10a, that is, increasing the amount of material that extends from between both syringers, and increasing the amount of material that extends. The trunk wall portion 5'b' formed by the fourth
As shown in the figure, the gap between the inner surface 3b of the lower cavity and the side surface 1b of the one-part no-lunger 1 is almost filled. That is, during the early stages of descent, material accumulates in the voids. If the pressing force is reduced and the downward movement is continued after the first stage has passed, the amount of material extending from between the two syringers will decrease, and tension will be added to the accumulated material on the barrel wall portion 5'b'. As a result, the trunk wall portion 5'b' is extended. Therefore, in the later stage of descent after the 1) fJ :lυ'' stage, the shell wall 5'b is stretched from between the material supplied by the stretching of the shell wall 5'b' during formation and the silane gloss. It is formed by the material that is produced.

Therefore, when the descent is completed, that is, when the hollow molded body 5' is formed, a gap 12 is formed between the body wall portion 5'b and the lower cavity inner surface 3bl, as shown in FIG.

By appropriately controlling the pressing force and the descending speed, a body wall portion 5'b having a substantially uniform thickness can be obtained. Thus 0.2
It is also possible to form a thin trunk wall portion 5'b. Since the pressing force at the latter stage of descent is relatively low as described above, the wall thickness of the bottom wall portion 5'C is relatively thick (
For example, about one or more corners), therefore, breakage of the corner portion 5'd due to tension during molding is prevented.

During the above molding, the step portion 3c, the bottom surface 4b of the presser, the lower cavity inner surface 3b1, and the upper surface 2 of the lower plunger 2.
a is maintained at a temperature slightly lower (typically 20 to 60°C) than the lower limit of the molecular orientation possible temperature of the molecularly oriented plastic, for example, about 60 to 100°C in the case of polypropylene, by a built-in heater (not shown).

After the hollow molded body 5' is formed, when the upper nolunger 1 is raised, the plug 8 is lowered by air pressure to fill the gap 20 between the plug 8 and the opening of the guide hole 7, as shown in FIG. Pressurized air is blown out, the hollow molded body 5' is blow-molded, and the bottom end 5'C is connected to the upper surface 2a of the lower sylanger 2.
Then, the body wall part s/b is brought into close contact with the lower key 1 and the inner surface 3b of the bit, and is cooled to a temperature lower than the temperature at which molecular orientation is possible.
harden. As shown in FIG. 7, the flange portion 5a
, a plastic container 5 having a body wall portion 5b1 and a bottom wall portion 5c.
is formed. After that, the upper plunger 1 continues to rise,
The presser 4 and the lower plunger 2 are raised to pull out the plastic container 5 from the die 3.

FIG. 8 shows the flange portion 5a of the plastic container 5 after being extracted, and its upper surface 5311 extends flatly in the radial direction. Therefore, the lid part t5 and the upper surface 5a
A sound heat 7-rule portion 16 can be formed over the entire surface of the heat 7-1.

On the other hand, as shown in FIG. 9, when a presser 4' whose entire bottom surface 4'b is flat is used, the upper surface 25a1 of the flange portion 25a sag as shown in FIG. The plastic container 25 (when the pressing force by the presser 4' is relatively small so as not to substantially reduce the thickness of the peripheral edge 10b of the blank), or the flange part a5a as shown in FIG. The pressing force by the presser 4' is applied to such an extent that the thickness reduction rate of the plastic container 35 (blank peripheral edge 1, Ob) in which a small raised part 36 has appeared on the upper surface 35a1, that is, a ridge has formed, is, for example, 30 inches. relatively large) is likely to form.

The reason for this is not necessarily clear, but if the above-mentioned pressing force is relatively small, in the later stage of forming the hollow molded body (corresponding to 5' in Fig. 5), the body wall part (corresponding to 5' in Fig. 5)
'b and 25'b in FIG. 9) is stretched, the flange portion (corresponding to 5a in FIG.
When the base of the flange (corresponding to 5'a) is pulled downward, and when the body wall expands by blow molding, a bending force acting diagonally downward on the outside acts near the base, and the upper surface 25 of the flange 'a l tilts slightly inward and downward, as shown in FIG. Since the pressing force is small, the presser 4' cannot sufficiently follow the displacement of the upper surface, so the above-mentioned problem cannot be corrected, and even after the presser 4' is released, the above tilt remains.
It is presumed that the phenomenon of "sagging" occurs.

On the other hand, when the above-mentioned pressing force is relatively large, the presser 4' descends following the displacement of the above-mentioned upper surface 25'a1.
A relatively large flow of material near the upper surface 25'aH occurs from the outer end radially inward, especially on the second surface 25'.
It is presumed that irregular internal stress occurs in the material near a 1, and as a result, after the flange portion 25'a is released from the presser 4', "undulations" occur as the internal stress is released. be done.

However, when the presser 4 is provided with the annular small protrusion 4b2, as shown in FIG. 10
(near the portion d) is restrained by the small protrusion 4b2 that engages with the biting portion 10d and is difficult to descend. Also, when the body wall part 5'b is expanded by blow molding to become the body wall part 5b, the first
As shown in FIG. 3, the base of the flange portion 5a is restrained by the small protrusion portion 4b2 that engages with the biting portion 10d, and is difficult to move diagonally downward to the outside. Therefore, the number of flange portions 5a during molding? i5a maintains a horizontal state regardless of the magnitude of the pressing force applied by the presser 4, and is unlikely to generate irregular internal stresses such as those described above, so even after the presser 4 is released, the flange portion 5
on the upper surface 5a1 of a,
This is thought to make it less likely to occur.

In order for the above-mentioned restraining force to work sufficiently, the small protrusion 4 must
The outer surface 4b2' (FIG. 12) of b2 must extend inwardly or upwardly in the axial direction.

Here, "substantially in the axial direction" includes a case in which it extends outward and upward at an angle of 20 degrees or less with the axial direction.

The larger the angle between the outer surface 4b2' and the axial direction of the outer surface 4b2' is, the greater the restraint force will be. It is desirable that the angle θ is 45 degrees or less.

Note that the height and maximum radial width of the small protrusion 4b2 are 0.
．． It is preferably within the range of 2 to 1.5 mm. Furthermore, the height of the small protrusion 4b2 is 1 of the thickness of the blank 10.
It is desirable that it is 0 to 25 inches. Appropriate values for the height and maximum radial width are determined experimentally in relation to the thickness of the blank and the width of the flange, respectively.

Note that it is preferable that the flat portion 4bl extends in the horizontal direction, that is, in the radial direction, or is slightly inclined outwardly (within an angle of 5 degrees with the radial direction) and downwardly.

The method of the present invention can also be applied to the production of cup-shaped plastic containers by the thermoformino method.

FIG. 14 shows an example of manufacturing a plastic container 45 with a flange portion 45a by vacuum forming. 4
3 is a die, and a vacuum suction hole 46 is formed at the bottom. 44 is a presser, and the flat part 44 of the bottom surface 44b
A small annular projection 44b2 similar to the small annular projection 4b2 is formed at the inner end of b1. The radial width of the bottom surface 44b is approximately equal to the sum of the width of the stepped portion 43c of the die 43 and the thickness of the plastic blank 40.

First, the plastic blank 4o heated to a predetermined temperature (preferably a temperature that allows molecular orientation) is placed on the stepped portion 43c, and then the peripheral edge 4, Ob of the blank 4o is held by the presser 4.
When the blank 40 is pressed by the blank 40 to form the biting part 404, when the air inside the cavity of the die 43 is sucked through the vacuum suction hole 46, the inside of the blank 40 from the biting part 4td is drawn. The central portion 40a is pressed upward by atmospheric pressure and press-fitted into the cavity, forming a plastic container 45. In this case as well, the displacement of the upper surface 45a1 of the flange portion 45a is restrained by the small protrusion portion 44b2, so after releasing the presser 44, a flat upper surface 45al of the flange portion extending in the radial direction can be obtained. Similarly, it goes without saying that the method of the present invention can also be applied to thermoforming methods such as pressure-air vacuum forming method and plug-assisted pressure-air vacuum forming method.The present invention is not limited to the above examples. For example, the annular small protrusion may be partially interrupted along the circumferential direction within the range where the above-mentioned restraining force is applied.

According to the method of the present invention, it is possible to produce a cup-shaped plastic container having a radially extending and flat flange upper surface suitable for the heat roll of the lid.

Examples will be described below.

Examples Melt flow index (measured at 230°C) is 0, 9.
9/10 minutes, melting point (differential calorimeter method) 164℃ thickness 3
A blank with a diameter of 74.5 mm was punched out and prepared from a polyzolopyrene sheet with a diameter of 74.5 mm. In the device shown in FIG. 1, the radial width of the bottom surface 4b is 4.5mm, the width of the flat portion 4bl (extending in the radial direction) is 4mm, and the height of the small protrusion 4b2 is 0.
．． 5+mn, maximum width 0.5■, angle θ of outer surface 4b2 (
Fig. 12) A presser shell 4 having an angle of 45 degrees was prepared. Note that a die 3 with a stepped portion 3c having a width of 4 mm in the radial direction was prepared.

The surface temperatures of the upper plunger (diameter 66.4 mm), lower granger (diameter 67.135 mm), lower cavity (inner diameter ＼ 68.1 mm), step part, and bottom of the presser are 120°C, 90°C, 75°C, and 120°C, respectively. It was preheated to 75°C using an internal heater.

After heating the polyzorozolene blank to 125°C,
As shown in FIG. 1, it was placed in the upper cavity and the peripheral edge of the blank was pressed with a pressure of 10 kV using a presser. Then, while applying a pressure of 180 kVC++2 to the center of the syringe blank using the upper sylanger and the lower plunger, the center of the blank was introduced into the lower cavity at a speed of 50cm, until the tip of the lower silane was 25 points from the top of the lower cavity. Pressure at the center of the blank is 90kg
Molding was performed while decreasing the temperature to 100 nm/cm until the tip of the lower sylanger was 100+ nm from the upper end of the lower cavity.

Then raise the upper syranja to 10kg/cm.
Air at a pressure of 2 was introduced to move the body wall surface of the molding container from the side surface of the upper plunger to the surface of the lower cavity to cool and solidify the body wall and the bottom wall. Thereafter, the presser and lower plunger were raised to obtain an extremely transparent container with a body wall thickness of 0.3 mm and a height of 99 mm.

The thickness of the flange portion was 2.9 mm, and the upper surface thereof was flat and extended in the horizontal direction, and no ``sag'' or ``ridges'' were observed.

Note that when the pressure of the presser was 140 kl$cm, the upper surface of the flange portion with excellent heat-sealability with the lid portion was similarly obtained, except that the thickness of the flange portion was 2 mm.

When the pressing force of the presser is 10 ky2y++2, the upper surface 2 of the flange part has a droop angle δ (Fig. 10) of 7 degrees.
5a1 occurs and the pressing force is 140 klz2, the height S of the raised portion 36 is 0.5a1. A flange portion upper surface 36a1 of '2m+n (FIG. 11) was obtained, and neither was satisfactory in terms of heat sealing with the lid.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view of a first example of the apparatus used for carrying out the present invention, and FIG. Figure 3 is a cross-sectional view taken along the line III--III in Figure 2, Figure 4 is a longitudinal cross-sectional view showing the early stage of molding using the apparatus shown in Figure 1, and Figure 5 is a compression view taken using the apparatus shown in Figure 1. 6 and 7 are longitudinal sectional views showing the state at the time when the stretch molding is completed and the hollow molded body is formed, respectively, during and after the blow molding of the hollow molded body shown in Figure 5. FIG. 8 is a vertical cross-sectional view of the main part of the device r shown in FIG. FIGS. 10 and 11 are longitudinal cross-sectional views of main parts showing an example of a state in which the formation of a plastic container has been completed using the apparatus, and FIGS. Longitudinal sectional view, 1st
2 and 13 are enlarged longitudinal cross-sectional views of the main parts near the flange of FIGS. 5 and 7, respectively, and FIG. 14 is a molding of a plastic container by a second example of the apparatus used for carrying out the present invention. FIG. 3.43...Dice, 3b...Lower cavity, 3
c, 43c...step part (shoulder part), 4.44...presser, 4b, 44-b...bottom surface, 4b2
144 bz...Annular small fire 71? Part, 5', 45...
・Cup-shaped plastic container, 5a + 45a...
- Flange part, 10.40...Plastic blank, 10 a r 40 a... Center part, 10b. 4 (1b--peripheral part, 10d, 40d... biting part. Fig. 1 Fig. 4 Fig. 5 Fig. 6 Fig. 7

Claims (1)

[Claims] (1) In a method for manufacturing a cup-shaped container with a flange from a blank made of thermoplastic plastic, the portion of the blank corresponding to the flange is connected to the shoulder of the die in the axial direction or inwardly. A small annular protrusion having an outer surface extending upward is pressed by a presser formed on the inner end of the bottom surface, and in a state where the small protrusion is injected into the blank to form a injection part, A method for manufacturing a flange portion+j cup-shaped container, characterized in that a portion of the flange from the injection portion to the inside 111!1 is press-fitted into the cavity of the die.